Liquid crystal displays are commonly used as display devices for compact electronic apparatuses, because they not only provide good quality images but are also very thin. Because liquid crystal molecules in a liquid crystal display do not emit any light themselves, the liquid crystal molecules have to be lit by a light source so as to clearly and sharply display text and images. Therefore, liquid crystal displays usually require a backlight module.
Referring to FIG. 9, a typical backlight module 9 includes a light guide plate (LGP) 90, and three light emitting diodes (LEDs) 92. The light guide plate 90 has a side surface 902 for receiving incident light, and a top surface 904 for emitting the light. The top surface 904 adjoins the side surface 902. The light emitting diodes 92 are disposed adjacent to the side surface 902 of the light guide plate 90.
In operation, light beams from the light emitting diodes 92 enter the light guide plate 90 via the side surface 902, and are converted by the light guide plate 90 to form a surface light source at the top surface 904. However, each of the light emitting diodes 92 has a certain limited angle of divergence of light beams emitted therefrom. Therefore areas of the light guide plate 90 beyond the angles of divergence of the light emitting diodes 92, such as areas A and B, may be relatively dark areas. That is, the surface light source of the backlight module 9 may be non-uniform, and the performance of an associated LCD may be visibly impaired.
What is needed, therefore, is a backlight module that can overcome the above-described deficiencies. What is also need is a liquid crystal display employing such a backlight module.